JP4004999B2 - Reciprocating power tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reciprocating power tool such as a reciprocating saw, and more particularly to a practical vibration damping technique that takes into account the behavior characteristics of a tool when a workpiece is actually machined despite a simple structure.
[0002]
[Prior art]
As an example of a reciprocating electric tool, Japanese Patent Laid-Open No. 2001-9632 (Patent Document 1) discloses a reciprocating saw configuration. The reciprocating saw according to this prior art has a structure that has a motion conversion mechanism for reciprocating a slider having a tool attached to the tip thereof through a rotational operation of a motor, and a counterweight is set in the motion conversion mechanism. ing. The counterweight is configured to reciprocate in the direction opposite to the reciprocating direction of the slider as the slider reciprocates, that is, with the phase shifted by 180 degrees relative to the reciprocating phase of the slider. The vibration at the time of reciprocating is reduced as much as possible to suppress the vibration of the electric tool.
[0003]
Since the counterweight reciprocates at the opposite phase to the reciprocating motion of the slider, the momentum mainly consisting of inertial force can be reduced between the slider and the counterweight in the long axis direction of the slider, and a reasonable vibration control can be achieved. Is possible. However, when the work material is actually cut using a tool and when the electric tool is driven in an idling state without being used for the cutting work, the counterweight is reduced depending on the presence or absence of external resistance acting on the tool. The optimal timing is different. Even during the work of cutting the workpiece, the external resistance acting on the tool has a certain amount of width due to various factors such as the pressing pressure when the operator presses the electric tool against the workpiece. Because of this, the timing of attenuation will vary depending on this width. On the other hand, if a method that responds finely to the timing of attenuation that differs depending on each work form is adopted, it is possible to effectively cope with these requests, but it is difficult to simplify the structure of the power tool, and the cost is reduced. Inconvenient cases may occur.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-9632
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and in a reciprocating power tool, it is simple to consider the behavior or characteristics of the tool when the workpiece is actually machined by reciprocating the tool. An object of the present invention is to provide a technique useful for effectively reducing vibration in spite of a simple structure.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in each claim is configured. According to the first aspect of the present invention, a motor, a tool that reciprocates to perform a predetermined processing operation on the workpiece, a slider that reciprocates to drive the tool, and a rotational output of the motor are output from the motor. A reciprocating power tool having a motion conversion unit that converts the reciprocating motion of the slider is configured. The “reciprocating power tool” in the present invention includes power tools used for processing various workpieces such as woodwork, metalwork, masonry, and various tools such as reciprocating saws and jigsaws. And The “motion conversion unit” widely includes a general motion conversion mechanism that can switch the rotation output of the motor to the reciprocating motion of the slider as appropriate.
[0007]
The motion converter has a counterweight that reciprocates opposite to the slider reciprocatingly. The counter weight is also referred to as “balancer”. Regarding the relationship between the slider and the counterweight that reciprocates opposite to the reciprocating motion of the slider, in the reciprocating power tool according to the present invention, the slider is electrically driven by the phase difference between the reciprocating motion of the slider and the reciprocating motion of the counterweight. The timing at which the top dead center moved most in the tool tip direction and the timing at which the counterweight reaches the bottom dead center moved most in the electric tool back direction are set to be fixed. The timing at which the slider reaches the top dead center is different from the timing at which the counter weight reaches the bottom dead center, so that the kinetic energy (momentum) due to the reciprocating motion of the slider is simply reciprocated with the counterweight reciprocating 180 degrees. Compared with the case of reducing the amount of vibration, the timing of attenuation due to the reciprocating motion of the slider is optimized while taking into account the machining resistance that the tool receives from the workpiece side during machining operations, and it is possible to take as much vibration suppression measures as possible. .
[0008]
In the present invention, the phase difference between the reciprocating motion of the slider and the reciprocating motion of the counterweight is set in a fixed manner so that the arrival timings at the top dead center and the bottom dead center of each member are different. For example, it is possible to adopt an embodiment in which a machining resistance that can occur most frequently in an actual machining operation is determined and fixed to a phase difference that is most expected to have a vibration damping effect in practice.
[0009]
In addition, the present invention adopts a configuration in which the phase difference between the reciprocating motion of the slider and the reciprocating motion of the counterweight is set to be fixed, so that the phase difference is adjusted in accordance with, for example, the processing resistance that the tool receives from the workpiece during processing. Comparing the structure of the reciprocating power tool can be avoided as compared with a mode in which it is variable as needed. In other words, it is possible to effectively reduce vibration in spite of a simple structure while considering the behavior or characteristics of the tool when the tool is reciprocally driven to actually process the workpiece.
[0010]
Regarding the early arrival timings of the top dead center, counterweight, and bottom dead center of the slider, for example, a tool that performs a reciprocating operation such as a tool that performs a cutting operation by push-cutting or a tool that performs a cutting work by pulling-off. Depending on whether or not the machining operation is performed, the timing of occurrence of machining resistance received by the tool from the workpiece varies, so the actual work mode is comprehensively judged and the slider top dead center arrival is below the counter weight. It is preferable to set a case where it is earlier or later than the dead point is reached.
[0011]
(Invention of Claim 2)
According to a second aspect of the present invention, the timing at which the counterweight reaches the bottom dead center with respect to the phase difference between the reciprocating movements of the slider and the counterweight in the reciprocating power tool according to the first aspect of the present invention is as follows. Are fixedly set so as to be delayed from the timing of reaching the top dead center . For example, when a workpiece is cut with a tool, the phase of the reciprocation of the slider due to the cutting resistance received by the tool from the workpiece is in an idle state where the cutting operation is not performed, that is, the tool receives resistance from the workpiece. It is easier to shift to the lag side than in the case of no load driving state. In addition, in the actual work site, the same type of machining work is often repeated, and thus the work resistance with respect to the reciprocating phase of the slider often becomes steady. Therefore, taking into account such steady working resistance, the counterweight reciprocating operation is relatively delayed from the state in which the phase difference of the reciprocating operation of the slider is opposite to the phase difference of the counterweight reciprocating operation. By setting so as to be fixed in a state where it is fixed, the maximum vibration damping effect can be obtained with a simple structure without complicating the structure of the reciprocating power tool.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the embodiment of the present invention, a reciprocating saw 101 will be described as an example of a reciprocating power tool as shown in FIG. As shown in FIG. 1, a reciprocating saw 101 according to the present embodiment generally includes a main body 103, a battery 105 that is detachably attached to the main body 103, and a front end side of the reciprocating saw 101 from the main body 103 (see FIG. 1). A slider 107 protruding in the middle right) and a blade 111 which is attached to a chuck 109 at the tip of the slider 107 and cuts a workpiece (not particularly shown for convenience) are mainly configured. The blade 111 corresponds to a “tool” in the present invention. The main body 103 includes a motor housing 103a, a gear housing 103b, and a handgrip 103c.
[0014]
A motor 113 (see FIG. 2) is disposed in the motor housing 103a that constitutes the main body 103. When the operator turns on the trigger switch 115, the motor 113 is driven. The workpiece 107 is configured to reciprocate in the left-right direction in the figure together with the slider 107 and the chuck 109 so that the workpiece can be cut.
[0015]
FIG. 2 shows a front cross-sectional configuration of the main part of the reciprocating saw 101 according to the present embodiment. In FIG. 2, the structure inside the hand grip 103c and the blade 111 are not shown for convenience. As shown in FIG. 2, the slider 107 having the chuck 109 provided at the tip thereof is supported by a bearing 107a so as to be able to reciprocate in the long axis direction (left and right direction in the drawing), and the gear housing 103b in the main body 103. It is connected to a motor output shaft 117 via a motion conversion mechanism 121 provided inside.
[0016]
The motion conversion mechanism 121 is a mechanism for converting the rotational motion of the motor output shaft 117 into a reciprocating linear motion in the long axis direction (left and right direction in FIG. 2) of the slider 107, and is a bevel gear 123, an eccentric pin 129, a crank 131, a guide. The pins 133 and the counter weight 139 are mainly configured. The crank 131 is a member that reciprocates the slider 107 and the counterweight 139 via the rotation output of the motor 113. The reciprocating phase of the slider 107 and the reciprocating phase of the counterweight 139 are 180 degrees different from each other. In view of the phase state, the phase of the reciprocating operation of the counterweight 139 is set to be delayed. This point will be described later.
[0017]
The bevel gear 123 is rotatably supported integrally with the rotary shaft 125 on the upper end side of the rotary shaft 125 that is pivotally supported by the bearing 127 and extends in the vertical direction in the drawing. A motor rotating shaft 117 is engaged with and engaged with the bevel gear 123. The eccentric pin 129 is screwed to the bevel gear 123 at a position where one end side thereof is shifted by a predetermined distance from the rotation center of the bevel gear 123. Further, the large-diameter head and washer of the eccentric pin 129 are set on the other end side, and the crank 131 includes a base portion 131a constituting the crank 131 and a large-diameter head and washer of the eccentric pin 129. And the bevel gear 123 to be integrated with the eccentric pin 129. Therefore, when the bevel gear 123 rotates around the rotation shaft 125, the crank 131 revolves integrally with the eccentric pin 129 that revolves around the rotation shaft 125 as the bevel gear 123 rotates. As a result of such revolution, the guide pin 133 attached to the tip of the crank 131 is located at the upper right of the rotating shaft 125 as shown in FIG. 2, and is located at the upper left of the rotating shaft 125 although not particularly shown. It is possible to operate between.
[0018]
The guide pin 133 is fixedly attached at the lower end in the drawing by being press-fitted into the distal end side of the slider drive part 131b constituting the crank 131. On the other hand, the upper end side of the guide pin 133 in the figure is fitted to a slider block 137 formed on the slider 107 via a bearing 135. The guide pin 133 is attached so as to be rotatable relative to the slider 107.
[0019]
As shown in FIG. 2 and FIG. 5 and FIG. 6 showing the side and bottom structure of the crank 131 in detail, the counterweight 139 is attached to the base 131a, which is a member constituting the crank 131, in a loose fit. The counter weight driving unit 132 is set. The counterweight drive unit 132 is configured as a cam-like element formed around a mounting hole 129a (see FIGS. 4 to 6) in which the eccentric pin 129 is fitted. Thus, the counterweight 139 is provided on the base portion 131a of the crank 131 that revolves around the rotation shaft 125 together with the eccentric pin 129 when the bevel gear 123 is rotated around the rotation shaft 125 via the motor output shaft 117. The counter weight drive unit 132 is configured to be able to reciprocate in the long axis direction (left and right direction in the figure) of the slider 107.
[0020]
As shown in FIG. 3 which is a plan view of the reciprocating saw 101, the counterweight 139 is formed with an elongated engagement hole 139a, and the revolution movement of the crank 131 around the rotation shaft 125 (see FIG. 2). Among them, the movement component in the direction intersecting with the long axis of the slider 107 in the horizontal plane is released to the long hole-like engagement hole 139a, and only the movement component in the long axis direction of the crank 131 is transferred to the counterweight 139. It is configured to be transmitted. That is, the counterweight 139 is configured to allow only reciprocation of the slider 107 in the long axis direction. As shown in FIG. 3, the counterweight 139 is configured to be slidably held by the slide guide portion 143 a of the holding plate 143 attached to the main body portion 103, thereby ensuring a reliable reciprocating operation. ing.
[0021]
2 and 3, regarding the reciprocating operation of the slider 107 and the counterweight 139, the most moved position in the tip direction of the reciprocating saw 101 (right direction in the figure) is the top dead center, and the back direction of the reciprocating saw 101 (left direction in the figure). ) Is defined as the bottom dead center. That is, slider 107 and counterweight 139 in the present embodiment are configured to reciprocate between top dead center and bottom dead center, respectively.
[0022]
As shown in FIG. 3 to FIG. 6, the crank 131 is configured as a member in which a base portion 131 a having the counterweight driving portion 132 and a slider driving portion 131 b are integrally formed. The crank 131 is driven to rotate in the counterclockwise direction (indicated by a symbol R in FIG. 4) about the rotation shaft 125 (see FIG. 2). The base 131a and the slider drive unit 131b are arranged around the rotation shaft 125. Are bent and integrated by an angle D. As a result, the rotational phase of the counterweight driving unit 132 is delayed by an amount corresponding to the angle D with respect to the rotational phase of the slider driving unit 131b. .
[0023]
The reciprocating saw 101 according to the present embodiment is configured as described above. Next, the operation and usage of the reciprocating saw 101 will be described. When the operator turns on the trigger switch 115 provided on the hand grip 103 c of the reciprocating saw 101 shown in FIG. 1, the motor 113 is energized and driven by the drive current from the battery 105. As a result, the motor output shaft 117 shown in FIG. 2 is rotationally driven. The rotation of the motor output shaft 117 causes the bevel gear 123 engaged with and engaged with the motor output shaft 117 to be rotated around the rotation shaft 125 in a horizontal plane. The eccentric pin 129 arranged offset from the rotating shaft 125 by the rotation of the bevel gear 123 revolves around the rotating shaft 125. As a result, the crank 131 revolves in the horizontal plane around the rotation shaft 125 together with the eccentric pin 129.
[0024]
As the crank 131 revolves, the guide pin 133 revolves around the rotation shaft 125 while rotating. The guide pin 133 is loosely fitted to the slider block 137 by a bearing 135, and the slider 107 is positioned between the top dead center and the bottom dead center in the major axis direction (left and right direction in FIG. 2) through the revolution of the guide pin 133. Are reciprocated linearly. The rotation operation of the guide pin 133 is received by the bearing 135 and is not transmitted to the slider 107 side. As a result, the blade 111 (see FIG. 1) attached to the chuck 109 provided at the tip of the slider 107 reciprocates in the long axis direction of the slider 107 to cut the workpiece.
[0025]
While the slider 107 reciprocates, a counterweight drive unit 132 provided on the base portion 131a of the crank 131 is used to reduce the kinetic energy (momentum) due to the reciprocating motion of the slider 107 and to control the reciprocating saw 101. The counterweight 139 reciprocates between the top dead center and the bottom dead center.
[0026]
By the way, in the state of cutting the workpiece by the reciprocating saw 101, that is, in the loaded drive state accompanying the cutting of the workpiece, in addition to the inertial force generated by the reciprocating movement of the slider 107, the chuck 109 and the blade 111 integrally, Furthermore, it becomes necessary to consider the influence of the resistance at the time of cutting that occurs between the workpiece and the blade 111. This is because the cutting resistance by the workpiece may cause a shift in the timing of killing by the counterweight 139.
[0027]
Specifically, the inertial force acts in the direction of travel of the slider 107, the chuck 109, and the blade 111, and the cutting resistance acts in the direction opposite to the direction of travel of these elements. The inertial force is defined based on the acceleration of the slider 107, the chuck 109, and the blade 111, while the cutting resistance is defined based on the speed of these elements, and there is a 90 ° phase difference between the two. Exist. Accordingly, since the force (cutting resistance) having a different phase is added as a function value having the speed as a variable to the inertial force by the slider 107, the chuck 109, and the blade 111, vibration suppression in the reciprocating saw 101 at the time of load driving is rational. In order to achieve this, it is necessary to consider not only the inertial force but also the cutting resistance received from the workpiece, taking these factors into consideration.
[0028]
The cutting resistance is defined based on the speed of each element, but the speed of each element in actual work varies within a suitable range depending on parameters such as the pressing force of the blade 111 on the workpiece. For this reason, it is possible that the mechanism of the reciprocating saw 101 is restrained by dealing with fluctuations in the cutting resistance one by one, which may lead to a complicated mechanism.
[0029]
As described above, in this embodiment, in order to take vibration suppression measures as much as possible without complicating the structure of the reciprocating saw 101, the cutting resistance value that appears frequently is determined, and then the base constituting the crank 131 is configured. The relative rotational position relationship between the portion 131a and the slider drive portion 131b is set to be fixed so that the counterweight 139 side causes a phase delay with respect to the slider drive portion 131b side by a predetermined angle D as shown in FIG. The phase difference between the reciprocating motion of the slider 107 and the reciprocating motion of the counterweight 139 is configured to correspond to a steady state. The predetermined angle D is an angle corresponding to the determined cutting resistance value, and is set to about 15 degrees in the present embodiment.
[0030]
As a result, in this embodiment, the phase of the reciprocating motion of the counterweight 139 corresponds to the angle D with respect to the phase of the reciprocating motion of the slider 107, as compared with the state in which the base portion 131a and the slider driving portion 131b are in series. It will be relatively delayed by the amount. In other words, by fixing the base portion 131a to a relatively delayed state with respect to the slider drive portion 131b and rotating it, the counter weight 139 is lower dead center than the timing at which the slider 107 reaches top dead center. It is driven so that the timing to reach is delayed. For example, FIGS. 2 and 3 show a state in which the slider 107 has already been driven to rotate beyond the top dead center when the counterweight 139 reaches its bottom dead center.
[0031]
According to the above-described embodiment, the relative positional relationship between the base portion 131a and the slider driving portion 131b is set to be fixed in consideration of a constant cutting resistance value that the blade 111 receives from the workpiece, As a result, the phase difference between the reciprocating operation of the slider 107 and the reciprocating operation of the counterweight 139 is set to be fixed so that the arrival timings at the top dead center and the bottom dead center of both members are different. Therefore, while taking into consideration the cutting resistance that appears most frequently in actual machining operations, it is fixed to a phase difference where the vibration damping effect can be most expected in practice, and as rational as possible without complicating the structure of the reciprocating saw 101 Can take anti-vibration measures.
[0032]
In the present embodiment, the counter weight 139 is fixed to a phase delayed by a predetermined amount from the opposite phase shifted by 180 degrees with respect to the phase of the slider 107. On the contrary, Further, it is also possible to suitably employ a configuration in which the phase of the reciprocating motion of the slider 107 is fixed to a state delayed by a predetermined amount with respect to the phase of the reciprocating motion of the counterweight 139. For example, it is possible to change the cutting operation of the blade 111 as appropriate according to whether the cutting operation is set to push cutting or drawing.
[0033]
In this embodiment, the reciprocating saw 101 has been described as an example of a reciprocating electric tool. However, the present invention can be widely applied to a form in which a workpiece is processed by reciprocating the tool, for example, a jigsaw. .
[0034]
In consideration of the above-described embodiment, the following modes can be configured.
(Aspect 1)
“The motion conversion unit is rotatable to convert a rotation operation by the motor into a reciprocating operation of the slider, and a rotation to convert a rotation operation by the motor into a reciprocating operation of the counterweight. A possible second motion converter,
The reciprocating motion is characterized in that the phase of the rotational motion of the second motion conversion unit is fixed in a state delayed from 180 degrees with respect to the phase of the rotational motion of the first motion conversion unit. Power tool. "
According to this aspect, the phase difference between the reciprocating motion of the slider and the counterweight can be easily set to a fixed state by adjusting the phase of the rotational motion of the first and second motion converters.
[0035]
(Aspect 2)
“A reciprocating power tool according to aspect 1,
The relative positions of the first and second motion converters can be switched from a state in which each motion converter is fixed at a predetermined relative position to a state in which the relative positions are fixed at different relative positions. A reciprocating electric tool characterized by comprising. "
According to this aspect, the relative position of the first and second motion converters is appropriately switched between a plurality of fixed states, so that the phase difference between the reciprocating motion of the slider and the counterweight can be easily switched and fixed. Is possible.
[0036]
Further, in the above-described embodiment, the base portion 131a and the slider driving portion 131b are configured as the crank 131 integrally formed in a bent shape, but the base portion 131a and the slider driving portion 131b are formed separately and screwed. It is also possible to adopt a configuration in which the crank 131 is configured by connecting with fastening means such as bolts or bolts. In this case, the phase of the reciprocating motion of the slider 107 and the phase of the reciprocating motion of the counterweight 139 are set different by loosening the fastening means and making the relative positional relationship between the base portion 131a and the slider driving portion 131b different. In addition, the fastening means is retightened, and the timing of attenuation by the counterweight 139 can be changed.
[0037]
【The invention's effect】
According to the present invention, in a reciprocating power tool, it is effective to consider the behavior or characteristics of the tool when the tool is reciprocally driven to actually process the workpiece, despite the simple structure. A technique useful for reducing vibration has been provided.
[Brief description of the drawings]
FIG. 1 shows an overall configuration of a reciprocating saw according to the present embodiment.
FIG. 2 is a partial cross-sectional view showing a configuration of a main part of the reciprocating saw according to the present embodiment.
FIG. 3 shows a configuration of a motion conversion mechanism in a plan view.
FIG. 4 shows a detailed structure of a crank in plan view.
FIG. 5 shows a detailed structure of the crank in a front sectional view.
FIG. 6 shows a detailed structure of the crank in a rear view.
[Explanation of symbols]
101 Reciprocating Saw 103 Main Body 105 Battery 107 Slider 109 Chuck 111 Blade (Tool)
113 Motor 115 Trigger switch 117 Motor output shaft 121 Motion conversion mechanism 123 Bevel gear 125 Rotating shaft 127 Bearing 129 Eccentric pin 131 Crank 131a Base portion 131b Slider drive portion 132 Counterweight drive portion 133 Guide pin 135 Bearing 137 Slider block 139 Counterweight

Claims (2)

A motor, a tool that reciprocates to perform a predetermined machining operation on the workpiece, a slider that reciprocates to drive the tool, and a motion converter that converts the rotational output of the motor into a reciprocating motion of the slider; A reciprocating power tool comprising:
The motion converter has a counterweight that reciprocates in opposition to the reciprocating motion of the slider,
The phase difference between the reciprocating motion of the slider and the reciprocating motion of the counterweight is the timing at which the slider reaches the top dead center where it moves most in the direction of the power tool, and the counterweight moves most in the direction toward the back of the power tool. A reciprocating electric tool characterized by being set in a fixed manner so that the timing of reaching the bottom dead center is different. The reciprocating power tool according to claim 1,
The phase difference between the reciprocating motion of the slider and the reciprocating motion of the counterweight is such that the timing at which the counterweight reaches the bottom dead center is delayed from the timing at which the slider reaches the top dead center. A reciprocating electric tool characterized in that it is set in a fixed shape.

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